<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无序列表</title>
</head>
<body>
<ul type="square">
  <li>动物
     <ul type="disc">
        <li>两栖动物1</li>   
        <li>爬行动物2
           <ul type="circle">
              <li>蜥蜴1</li>
              <li>壁虎2</li>
           </ul>
        </li> 
     </ul>
  </li>
  <li>植物</li>
</ul>
</body>
</html>